package com.filter;

import java.io.IOException;
import java.util.Enumeration;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

public class AntiSqlInjectionFilter implements Filter {

	public void destroy() {
	}

	public void init(FilterConfig arg0) throws ServletException {
	}

	public void doFilter(ServletRequest args0, ServletResponse args1,
	FilterChain chain) throws IOException, ServletException {
		HttpServletRequest req = (HttpServletRequest) args0;
		// 获得所有请求参数名
		@SuppressWarnings("rawtypes")
		Enumeration params = req.getParameterNames();
		String sql = "";
		while (params.hasMoreElements()) {
			// 得到参数名
			String name = params.nextElement().toString();
			// 得到参数对应值
			String[] value = req.getParameterValues(name);
			for (int i = 0; i < value.length; i++) {
				sql = sql + value[i];
			}
		}
		// System.out.println("============================SQL"+sql);
		// 有sql关键字，跳转到error.html
		if (sqlValidate(sql)) {
			throw new IOException("您发送请求中的参数中含有非法字符");
			// String ip = req.getRemoteAddr();
		} else {
			chain.doFilter(args0, args1);
		}
	}
	// 效验
	protected static boolean sqlValidate(String str) {

		str = str.toLowerCase();// 统一转为小写

		String badStr = "'|and|exec|execute|insert|select|delete|update|count|drop|*|%|chr|mid|master|truncate|"
				+
				"char|declare|sitename|net user|xp_cmdshell|;|or|-|+|,|like'|and|exec|execute|insert|create|drop|"
				+
				"table|from|grant|use|group_concat|column_name|"
				+
				"information_schema.columns|table_schema|union|where|select|delete|update|order|by|count|*|"
				+
				"chr|mid|master|truncate|char|declare|or|;|-|--|+|,|like|//|/|%|#";// 过滤掉的sql关键字，可以手动添加

		String[] badStrs = badStr.split("\\|");
		for (int i = 0; i < badStrs.length; i++) {
			if (str.indexOf(badStrs[i]) >= 0) {
				return true;
			}
		}
		return false;
	}
}
